THE SIR PROVIDED THIS PROJECT WITH 50MG OF [U-13C, 15N]PQQ. THIS PROJECT EXAMINES THE CHEMICAL MECHANISM OF THE PQQ-DEPENDENT METHANOL DEHYDROGENASE FROM THE METHYLOTROPHIC BACTERIUM METHYLOBACTERIUM EXTROQUENS AM1. PQQ IS ONE OF A FAMILY OF O-QUINONE ENZYME COFACTORS NOW KNOWN TO BE INVOLVED THE ENZYMATIC OXIDATION OF ALCOHOLS AND GLUCOSE. DURING THE OXIDATION OF SUBSTRATE BY METHANOL DEHYDROGENASE, THE ALCOHOL IS THOUGHT FORM A HEMI-KETAL AT THE C-5 CARBONYL OF ENZYME BOUND PQQ. IN ADDITION, INHIBITORS OF THE ENZYME SUCH A CYANIDE AND O-AMINES ARE THOUGHT TO ACT AS NUCLEOPHILES AND FORM ADUCTS WITH THE CARBONYLS OF PQQ. WE HAVE CARRIED OUT MODEL REACTIONS WITH [U-13N,15N]PQQ WITH METHANOL AND CYANIDE. THE STRUCTURE OF THE PRODUCTS WAS DETERMINED USING 13C COSY NMR SPECTROSCOPY. METHANOL FORMS AN ADDUCT EXCLUSIVELY AT THE C-5 QUINONE.